Friday, September 30, 2011

In a new study, researchers used a type of brain scan called fMRI to record brain activity in three people as they watched hours of Hollywood movie trailers. Brain signals were fed into a computer program that learned how each person’s visual system responded to scenes in the movies. Once the computer program had a good handle on the brains’ responses, the researchers went backwards and attempted to re-create what people were watching solely on the basis of brain signals. The basic physics of an fMRI isn’t difficult. A patient is first of all placed inside a large magnet and radio waves are then used to excite the nuclei of hydrogen atoms within the patient's body using an external coil. After this step of applying radio-frequency excitation, the hydrogen atoms emit energy at the same radio frequency until they gradually return to their equilibrium state. These radio waves are detected using an external coil, measures the sum total of the emitted radio-frequency energy, digitized, processed by a computer and displayed as tomographic slices revealing the distribution of different tissues.

Right now, the technology only allows for the detection of stationary objects and doesn’t read emotions. However, if we combine the ever increasing potential of brain scan technology and the ease in which computers can scan through large amounts of data in no time at all, there could come a time where any scanner will be able to read exactly what you are seeing, thinking and feeling. Welcome to the future of technology.

At ~90/95 mph, the ball travels from the pitchers mound to the plate (60ft. 6in) in 400 milliseconds. After calculating the time it takes to look and think, the batter only has a quarter of a second to decide what to do or not and start the swing. The swing itself takes 150 milliseconds, so the batter must start his swing approximately 25-30 ft in front of the plate. The ball will arrive at the plate about a quarter of a second later. Test you reaction skills and whether or not you could make the 90 mph hit here: http://www.exploratorium.edu/baseball/reactiontime.html

The margin of error is a whopping 7 milliseconds- too early or too late and you'll hit it foul. So next time you're watching baseball and a player hits a 90 mph fastball, appreciate how hard that is to do.

Thursday, September 29, 2011

“You have to commit. Keep your speed up. Start to twist before you leave the ground; if you don’t you’re not going to make it.” My coach’s words played over and over as I slide away from him and began moving down the mountain. The jump was in front of me; I tried to listen to my coach’s advice, but I couldn’t subside the fear that was building inside me. The closer I came to lip of the jump, the more I doubted my coach, the less committed I became. I thought he just wanted me to ‘go big’. I thought he was being reckless. I thought I knew better… I was wrong.

I didn’t commit. I didn’t keep my speed up. I didn’t start to twist before I left the ground. The advice my coach gave me that I labeled reckless was really just physics. From the time I began to slide away from him, I was converting potential energy to kinetic energy—kinetic energy that could have been conserved while I was in the air over the jump—kinetic energy that would have helped me clear the jump. The conservation of angular momentum was the physics behind the need for pre-jump twist. Without initial rotation, there was no angular momentum to let me finish my spin.

Physics are the guiding principles behind all aspects of snowboarding, and whether conscious of it or not, knowing how to snowboard requires a knowledge of physics. As already mentioned, the conversion of potential energy to kinetic energy allows for movement down the mountain (with consideration given to components based on the steepness of the trail). Friction of the snow or ice, the particular base of the snowboard, the wax applied to the base, etc. all play a part in determining acceleration down the mountain. Friction also is a big factor in the park; rails and boxes have varying coefficients of friction. Approaching a rail, your board is interacting with the snow and that’s what dictates the force of friction in the opposite direction of your movement. This changes quickly when you move from snow to the metal or plastic of rails and boxes. Not only does this require an adjustment to your center of gravity and balance, but also the change in the coefficient of friction can either increase or decrease your acceleration, sometimes very abruptly.

Though my coach’s words of wisdom seemed counterintuitive at the time, physics explains his reasoning; I accused him of being reckless, but without following his advice it was physically impossible for me to clear the jump and finish my rotation. - post written by Kate Homan.

Wednesday, September 28, 2011

As we all know, on September 11, 2001, two planes struck the twin towers in New York City causing their collapse. What some people don’t know is that another building fell that day, a building located at 7 World Trade Center. The cause of its collapse is heavily disputed still today. Many argue that the building collapsed after fire from the neighboring Trade Center caused the steel to melt, compromising its structural integrity. This is what the national reports claim caused the fall. But according to this video, and many other conspiracy theories, something else was at play here.

http://www.youtube.com/watch?v=7wI1BNgXskM

This video explains the argument many physicists about the building’s collapse. As you can see in the video, the initial collapse was in column 79. Shortly after, the remainder of the building falls down simultaneously. If the framework of the building had melted, it seems strange that the entire building would have collapsed at the same exact time. You can see how the roof line stays intact during the fall. The calculated values of the acceleration of the building’s collapse, do not match up with the actual time it took for the building to fall. Physicists use these numbers to argue that the building must have been in free fall. In other words, there was no resistance underneath of the building during the collapse. The only way that this could be possible is if there was an explosion underneath, allowing limited resistance for the fall. This theory will probably never be accepted as truth by the national government as it would imply that this was an inside job. - post written by Lauren Dittman.

Tuesday, September 27, 2011

While going through my email I saw a message from a bowling ball website and when I
thought about it I realized that a lot of things in bowling can be explained through physics. I did
some research and found a website that explains in great detail the many different physics
properties that go into bowling.

http://www.real-world-physics-problems.com/physics-of-bowling.html

The physics in bowling starts with the actual ball itself. There are two different types of weight blocks
in the balls, a symmetrical block and an asymmetrical block. The symmetrical block is even on all sides and so if thrown normally the ball will roll straight. The asymmetrical block has an uneven weight ratio so when thrown normally the ball will curve one direction depending on the weight distribution of the block. Friction and potential energy are also important in bowling. When a bowler throws a curve ball the ball slides down the oil on the lane gaining potential energy the entire time. When the ball hits a point on the lane where there is little oil the surface of the ball has friction in the lane and this causes the ball to change direction. When the ball hits the pins all the potential energy stored in the ball is distributed to the pins causing them to fly in every direction. Different bowlers roll the ball in different ways by using balls with different surfaces as well as differing their approaches and the way they rotate their hands around the ball upon release.

http://www.youtube.com/watch?v=50PTlqvBlE8&feature=related

Using their knowledge about bowling, which is instinctively due to physics bowlers are able to create trick shots such as the flying eagle.

Sunday, September 25, 2011

I was watching YouTube videos on the greatest soccer goals ever scored and found this free kick scored by Roberto Carlos in the 1998 World Cup against France.Roberto’s shot, approximately 30 meters from the goal, curves around the wall, outside the frame of the goal, and off the post.Maybe without knowing it, Roberto is taking advantage of several physics concepts that allow him to “bend” the ball into the goal.

The curve of a soccer ball, or any sport ball, can be explained by fluid dynamics, the Magnus effect, and Bernoulli’s principle.The Magnus effect is a perpendicular force in the direction of low pressure created by a spinning object and fluid. By kicking the ball with a force on the outside of the ball, Roberto makes the ball spin counterclockwise which results in the boundary layer of air being dragged around the ball. Bernoulli’s principle states “where the velocity of a fluid is high, the pressure is low, and where the velocity is low, the pressure is high.” The side of the ball rotating against the air creates a lower velocity of fluid and a higher pressure.The side of the ball rotating with the air creates a higher velocity of fluid and a lower pressure, resulting in a force in that direction.This force helps the ball “bend” around the wall and into the goal.

Thursday, September 22, 2011

There was an article this morning on AOL that talked about a baby penguin born without feathers and abandoned by his family. He didn't have the proper nutrition to allow for feather growth. I always assumed that feathers were important to a penguins survival, but wasn't certain on what they actually did. I started looking into what feather did for penguins and learned something interesting about how penguins use there feathers to get out of the water.

Emperor Penguins are flightless birds but can often be seen leaping out of the water so high that they look like they are flying. This is leaping is necessary because the shape of penguins (torpedo), there instability on land, and the limited use of their wings outside of water make it impossible for a penguin to lift themselves over the ice back on to the land. However what was determined was that the speed at which the penguins exited the water was much to high to be accounted for by only buoyancy factors. They exit the water at about 5.3 m/s. So physicist attempted to determine how it was that they are able to exit the water so quickly and what they used other than buoyancy.

What was determined was that the air bubble stream that is seen behind them prior to exiting the water is actually air released from there feathers. The penguins clean and fluff there feathers prior to entering the water allowing for lots of air to be stored. Then when wanting to exit the water they depress there feathers. The air expelled increases there speed and decreases there drag. This causes them to have enough speed to propel out of the water and fly through the air onto the ice. This uses the physic properties of fluid dynamics, air lubrication, and buoyancy.

On a side note the veterinarians at the zoo were able to fix the nutrition problems of the penguins allowing him to grow feathers and return to his family.

Although our eyes can’t tell, vibrating guitar strings behave as standing waves that set the surrounding air into similar vibrational motion, which produces sound waves that ultimately travel into our eardrums. Unsurprisingly, the frequency (# of vibrations per second) of the vibrating string equals the frequency of the sound waves. Hence, a high frequency vibration produces a high pitch note, while a low frequency vibration produces a low one.

So what determines the frequency of the vibrating guitar string? There are multiple factors. First, a higher mass, in this case the thickness, of the string causes it to vibrate at a lower frequency. Second, raising the tension in the string by tightening the tuning pegs increases its vibrational frequency. Last, a shorter length of the string, achieved by placing a finger on particular frets, also indirectly increases the frequency by raising the tension.

Follow the URL below to check out a cool YouTube video captured through an iPhone that shows the wave properties of vibrating guitar strings:

Wednesday, September 21, 2011

In September 1991, NASA deployed the Upper Atmosphere Research Satellite (UARS) from the space shuttle Discovery. Its purpose was to measure chemical compounds in the ozone layer, atmospheric winds and temperatures, and energy produced by the Sun. These measurements helped scientists determine the role of the upper atmosphere in climate regulation. After 14 years of gathering data, the UARS was decommissioned on December 14, 2005. Scientists left it floating around in space with the knowledge that it would eventually return to Earth. The "eventually" is now close at hand. This Friday, to be specific.

On Friday, chunks of the UARS that do not burn up during re-entry will come crashing down to the Earth's surface. NASA analysts estimate a total of 532 kilograms of satellite components will be landing somewhere between 57 degrees North latitude and 57 degrees South latitude, a gap from Alaska to the southern tip of South America. Do not worry about being hit by a piece of satellite though. NASA has calculated the chance of 1 in 3200 that a person would get hit, and 1 in 22 trillion that that person will be you.

How can they know that? By using the physics of falling objects, universal gravitation, and knowing the masses and velocities of the pieces that will soon be hurtling towards Earth. It's still kind of a long shot, but considering how much of the Earth is covered in water, plus adding in the uninhabitable areas like deserts and high mountain ranges, the regions where a satellite fragment might actually hit a person are drastically reduced. NASA will have to be tracking the satellite during its re-entry in order to really know exactly where the pieces are going to land. Hopefully we will get to see some part of the process, for it will be - as the Science author put it - like "a $750 million fireworks display."

Tuesday, September 20, 2011

In recent years, there have been numerous advances in naval technology. Here are a few examples:

This past Saturday the U.S. Navy endorsed the joint high speed vessel, Spearhead, a fast cargo ship for the transportation of troops, vehicles, and supplies. Spearhead can operate in shallow water up to an average speed of 35 knots (~40.3 mph) while carrying a full load of 1.2 million lbs.

In August of this year, the U.S. Navy revealed the new stealth boat, Ghost, designed for speed and stealth ideal for special ops. The boat is capable of achieving up to 60 mph by generating “a layer of gas around its underwater surfaces” or a phenomenon called supercavitation, which reduce friction by a factor of 900. As for stealth, the shape of the ship, like stealth plane, is designed to make radar waves bounce off away from the sender to achieve the invisibility.

And lastly, in April of this year, the U.S. Navy had successfully installed and used ray gun or high-energy laser weapon. The purpose is to protect military vessel from tiny suicidal boat like the one that almost sunk the destroyer U.S.S. Cole in 2000. The laser works by “slowly” burning a hole through a boat’s engine. Although it is less efficient than an M16, the progress is still impressive because in the past, laser weapons have limited success as laser beam intercepts dust in the air and lose focus. The problem is even more severe closer to sea level as dust gets more concentrated. So this marks a progress.

This season, the NFL has changed several rules to try to reduce player injuries, especially concussions. Research done by a team at Purdue on football injuries has shown that in a typical hit, a player can experience around 40 g's, and in "big hits," players may experience almost 300 g's, measured by sensors in helmets.

One of the new rules is that kickoffs are now 5 yards closer, meaning defending players will now have 5 yards less distance to run before engaging in tackles. The idea behind this is that players running down the field after a kickoff will have less velocity before making tackles, which would reduce the acceleration players experience during hits.

Concussions are a result of the brain experiencing a rapid deceleration after colliding with the inside of the skull. The brain is surrounded by fluid, so it can move around inside the skull relatively independently of the head itself.

Wednesday, September 14, 2011

For many ballet is a form of art, something to be perfected through years of training. For Ken Laws, ballet is a game of physics. Law is a physics professor at Dickinson College, and he also teaches ballet classes. When he believes students could be performing a step better he explains to them, in terms of physics, how to correct their movement.

Three steps are discussed at length in the article, a grand jete en tournant, and fouettes. The videos below show these movements:Grand jete en tournant:http://www.youtube.com/watch?v=rmj8H0waXyQGrand jete:http://www.youtube.com/watch?v=oHivyA_fwpAFouettes:http://www.youtube.com/watch?v=bOdE0P7K0HM

Laws explains that when performing a grand jete en tournant, one must use the torque of their body to turn through the air. He says the dancer's angular momentum is equal to the rate of spin multiplied by the moment of inertia (which depends on how the dancer's mass is distributed around her spin axis). The 180 degree turn can be turned into one and a half turns by bringing the legs together at the top of the turn, bringing the legs and arms into the axis of rotation, and holding them there. Conservation of angular motion allows the dancer to then complete the extra rotations.

The grand jete is a perfect parabola. Laws says that once the dancer leaves the floor there is no way to alter the path taken, however, by opening the legs when nearing the top and closing them while coming down from the jump, the dancer uses her legs to "take up most of her center of gravity's vertical motion."

Finally, in the fouette turn, the whipping leg stores momentum as the dancer turns and then returns it to the body by tucking it back in. It is also important to note that when the dancer rises in a balance their body must be perfectly perpendicular to the ground in order to sustain the position - this way their center of gravity will remain in tact.

Laws argues that conservation of motion is the most important physical principle in ballet as it can be applied to many jumps and turns. His application of the rules of physics to ballet allows him to not only give form corrections to dancers, but to explain how altering their movement according to the laws of physics can help them to correctly execute the step.

Tuesday, September 13, 2011

A team of scientists at Georgia Institute of Technology published a paper in Fluid Dynamics examining the optimum speed and frequency at which dogs should shakes themselves to dry off. For the hair to dry, its tangential acceleration must exceed the surface adhesion between the hair and the water. The hair has to move fast enough to slip out from under the water and allow the water to fly off. Centripetal force varies depending on the radius of the dog. This helps explain why the frequency of oscillation is different for different sized animals.

Dogs were filmed shaking themselves dry with a marker placed on their skin to track its movement. They analyzed videos of many other animals as well. They found that the frequency of oscillation ranged from 27 Hz in mice to 4 Hz in bears. The relationship between frequency and size was not linear, but approached 4 Hz asymptotically. When graphed, the angular position of the skin makes a sinusoidal pattern. - written by Janna Minehart

Monday, September 12, 2011

On Wednesday, September 7th, a Russian plane carrying the entire Lokomotiv Ice Hockey Team from Yaroslavl, Russia to Minsk, Belarus crashed, killing 43 out of 45 of the people on board. Since the day of the crash, officials have been trying to discover its causes. Logically, the plane crashed because of one of two reasons; there was either pilot error or technical error involved.

One of the most common of the technical errors that cause planes to crash is the malfunctioning of the stabilizers and flaps on the wings of the plane. Planes stay airborne because of Bernoulli’s Principle, which states that faster moving fluids exert less pressure than slower moving fluids. An airplane’s wing is shaped in a way that causes the air travelling over the wing to go a farther distance than that going underneath the wing in the same amount of time. This forces the air on top to move faster than the air on bottom, and therefore the air on top exerts less pressure on the wing than the air on the bottom. The higher pressure below the wing literally pushes the plane up because the counteracting force from above is much less. This is Bernoulli’s Principle in action.

Flaps and stabilizers alter the pressure differences between the areas above and below the wing, causing the airplane to turn or go up and down. Faulty flaps or stabilizers will cause the pilot to lose control of the plane, inevitably resulting in a crash.

Another common technical error in airplanes is engine failure. When a plane’s engine fails, it loses its forward thrust and is slowed down by intense air resistance. In order for Bernoulli’s Principle to work on an object as massive as an airplane, there must be a large speed involved. As the plane is slowed, the air on top of the wing does not travel as fast and pressure increases. This starts to equalize the pressure above and below the wing, and the plane starts to drop. Engine failures can be brought about by many different reasons, such as faulty wiring or poor quality fuel.

Recent reports show that the Russian plane’s stabilizers and flaps were in their proper position until impact, and its engine was running properly the whole time. This means that the plane crash was most likely the result of pilot error. - written by Rob Tardif

Friday, September 9, 2011

Just to re-cap the awesome time presentation in class today, the ten things every science student should know about time are:1) Time Exists.2) The past and the future are equally real.3) Everyone experiences time differently.4) You live in the past.5) Your memory isn't as good as you think.6) Consciousness depends on manipulating time.7) Disorder increases as time passes.8) Complexity comes and goes.9) Aging is reversible.10) A lifetime is a billion heart beats.To get a much more detailed explanation on all the following points/ vent your frustrations about some of them, do visit the blog which actually published the article at http://blogs.discovermagazine.com/cosmicvariance/2011/09/01/ten-things-everyone-should-know-about-time/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+CosmicVarianceBlog+%28Cosmic+Variance%29

Wednesday, September 7, 2011

Explosive volcanoes can be incredibly hazardous as the shoot projectiles including ash and rock fragments into the air often sustaining large columns (like the one from iceland that shut down air flight). The explosive character of this type of volcano is all based on physics. In the magma chamber there is melt and the composition of this melt includes dissolved gasses. There are two types of "boiling" that aid explosivity.

The first type is called "first boiling." This type is similar to when you shake up a soda bottle and then open the top.If some how a little pressure is released, for example the rock infrastructure of the volcano cracks, the decompression will lower the confining force.When the confining force decreases the vapor pressure of the dissolved volatiles may be able to over come the confining pressure and exsolve from solution.This creates all the bubbles that form when a soda bottle is opened.Second boiling results from when minerals start to crystallize out of the melt.This increases the percent of dissolved gasses in the melt and as a result increases vapor pressure.When vapor pressure exceeds the confining pressure, once again gasses will exsolve from the melt.If the magma is highly viscous the bubbles cannot readily escape and as a result will increase the overall pressure in the magma column.Eventually vapor pressure will exceed the confining pressure of the melt and rock around the magma chamber and the volcano will explode fragmenting the rock and melt and projecting it into the air.

As you can see pressure and the physics behind pressure is what triggers and then drives an explosive eruption.

Last week's New York Times Sports section featured a number of articles about Venus Williams' sudden exit from the US Open after announcing her diagnosis of Sjogren's Syndrome. Sjogren's Syndrome is a disease in which the body overproduces B lymphocytes which in turn clog the body's moisture glands. This disease is often difficult to diagnose because, like Venus, it can arise in people who appear to be perfectly healthy but are experiencing symptoms such as fatigue and joint pain.

Some patients with Sjogren's have difficulty sweating due to the obstruction of their sweat glands from the overwhelming prevalence of B lymphocytes. A Sjogren patient's athletic performance and energy levels can be greatly impacted by the inability to sweat, which can be explained by a principle in physics: a phase change from liquid to vapor and water's high heat of vaporization.

Due to water's very high heat of vaporization, humans can release a significant amount of heat from their bodies, which is produced by metabolism and working muscles, during exercise. This can be understood by the equation for a phase change, Q=mL (heat=mass*latent heat of vaporization). The large amount of heat that the evaporation of sweat can release allows our bodies to cool in temperature giving us the capacity to tolerate what would otherwise be potentially dangerous increases in body temperature.

Especially in Venus' case, Sjogren patients who are physically active should look into how to best treat their condition. Attempting strenuous activity in high temperatures without the ability to release the body's heat through sweat has a high risk for heat-related illnesses such as heat exhaustion or death.- post written by Michelle White

Over the past few years, I have eagerly pursued a childhood dream of mine to write and record an entire music album by myself.The long college summers have given me ample time to finish writing and arranging plenty of material for an album, but I have recently discovered that using home recording equipment does not produce the quality and essence of sound that I strove to record in the first place.

Over the past decade, the process of recording and enjoying music has become extremely digitized.Though compact discs contain high quality WAV files, many music fans (myself included) have decided to sacrifice sound quality for convenience purposes by downloading lower quality music files from iTunes or Limewire—after all, it’s hard to hear all the subtleties of music through iPod ear buds, so it really doesn’t matter to most people.Musicians have also begun recording music digitally, using programs such as Pro Tools and Garage Band.Instead of placing a microphone near their amplifiers, guitarists such as myself have been able to purchase guitar cables that connect directly to the computer from the guitar.

Though these cables are extremely convenient, many musicians complain that their guitars do not sound nearly as good when digitized.They feel that the recording programs have failed to capture guitar tone and style as well as they would have liked.However, engineers at the Fraunhofer Institute for Surface Engineering and Thin Films IST have created a device that is extremely accurate at picking up the intricacies of how a guitar is played.

The device is called DiaForce, and it is a thin film coating that covers the tailpiece (also known as the bridge (see above)) of the guitar.Saskia Biehl, the head of the micro and sensor technology group at the Fraunhofer Institute explains that the DiaForce is so effective because it is able to accurately detect changes in string tension.He says, “When the guitarist changes string tension, the pressure on the film changes,” thus leading to a highly specific and accurate representation in the digital recording program.Biehl and his coworkers also seek to measure strength of string vibration as a way to record stroke strength and the fading of note amplitude over time.

Biehl and his coworkers believe it is possible that one day DiaForce will be found on all guitars and pickups will no longer be necessary.This is a shocking thought, considering pickups have been on guitars for many decades, but this film covering may in fact revolutionize the sound of guitars and how we record and enjoy music.Perhaps one day I will be able to achieve the tone I desire using digital recording software thanks to the DiaForce.

Sunday, September 4, 2011

The site that I used to find my physics news article was Science Daily. On this site I found and interesting article about an extreme weather pattern that occurred in July of 2010 and has now been explained by physics.

The article explains how the heat wave and drought experienced in Russia in 2010 was also connected to the severe flooding and monsoons that occurred in Pakistan that same year. A stagnant weather pattern called an Omega blocking event developed over a high-pressure ridge above western Russia. This blocking event, which divided the jet stream, had the effect of slowing the Rossby wave and prevented the normal progression of weather systems from west to east. As Earth spins on its axis Rossby waves meander around the globe in a westerly direction. Currents in the center of these waves form the jet streams, fast-moving columns of air that push weather systems from west to east. The event caused high pressure to form over Russia and trap a hot, dry air mass. As the high lingered, the land surface dried and the normal transfer of moisture from the soil to the atmosphere slowed. The blocking pattern also created unusual downstream wind patterns over Pakistan. Areas of low pressure on the leading edge of the Rossby wave formed in response to the high that pulled cold, dry Siberian air into lower latitudes. The shift led to heavy monsoon rains over the northern part of Pakistan.

Overall, the physical interactions of the Coriolis effect and pressure gradients are responsible for our weather patterns. Slight deviations from the normal Rossby waves can have large impacts on the regional weather we experience.